A ground vehicle equipped for automated steering control may include a navigation control system coupled with a Global Positioning System (GPS) receiver assembly or the like. Data from the GPS receiver is used to determine an off-track error, for example, a measurement of the distance the vehicle has diverged from its intended track. A heading error is also determined as a measurement of a difference between the ground vehicle's measured heading and its intended direction. Finally, instrumentation may be provided for measuring a wheel angle for the vehicle. The off-track error, heading error, and wheel angle may be input to several nested proportional control loops, in combination with an integral controller on an outer loop, for providing automated steering control for the ground vehicle.
State of the art automated steering control systems are subject to several limitations. For example, the use of proportional control loops and a proportional integral control loop may not provide a robust solution over a wide range of vehicle speeds. The control loop utilizing vehicle heading information typically requires vehicle speed compensation. Additionally, those of ordinary skill in the art will appreciate that measured wheel angle is not a true indication of steering effectiveness, because of the effects of wheel slip, and the like. Consequently, it would be advantageous to provide a system and method for controlling a ground vehicle, such as for automated steering control of the vehicle, without requiring a measurement of the ground vehicle's wheel angle or the like which would be effective regardless of the vehicle's speed.